Year	Percent
1990	32.181
1991	32.204
1992	32.162
1993	32.059
1994	32.031
1995	31.953
1996	31.95
1997	31.994
1998	32.012
1999	31.996
2000	31.94
2001	31.912
2002	31.89
2003	31.873
2004	31.862
2005	31.854
2006	31.846
2007	31.873
2008	31.867
2009	31.818
2010	31.811
2011	31.831
2012	31.811
2013	31.772
2014	31.765
2015	31.771
2016	31.839
2017	31.867
2018	31.901
2019	31.934
2020	31.963
2021	31.992
2022	32.014
2023	32.033
2024	32.051
2025	32.073
2026	32.098
2027	32.123
2028	32.146
2029	32.166
2030	32.183